Data fusion is a process aimed at combining several data sources to accomplish a task more reliably than it would be possible with just one individual sensor. This has several useful applications, ranging from medical diagnostics [1]} to robotics [2]} and smart buildings [3]}. Tracking one or more speakers by means of acoustic and visual sensors also relies on an appropriate fusion of sensory inputs. This process is performed unconsciously in human listening, since humans naturally combine visual and acoustic stimuli in estimating the position of a person speaking or a sound source emitting noise [4]}.
